Implementing publish/subscribe pattern for CoAP in fog computing environment

As more and more Internet of Things (IoT) devices are connected to the cloud services, fog computing has emerged as a new computing model to provide analytic and intelligent services to the end users for fast response time. Among the application layer protocols used for IoT, MQTT and CoAP are two well-known lightweight protocols that run on top of TCP and UDP, respectively. MQTT supports publish/subscribe pattern, while CoAP adopts request/response pattern. In IoT applications, publish/subscribe model was thought as a better model due to lower network bandwidth and less message processing which in turn extending the lifetime of battery-run devices. In this paper, we implement the publish/subscribe pattern in fog computing to preserve the privacy of customer energy usage data in smart grid environment using CoAP as the underlying application layer protocol. The performance of CoAP vs. MQTT in this model is also reported.